The Lord Keeper of the Great Seal of England, and later of Great Britain was formerly an officer of the English Crown charged with physical custody of the Great Seal of England. This evolved into one of the Great Offices of State.

The seal, adopted by Edward the Confessor was at first entrusted to a chancellor for keeping. The office of chancellor from the time of Becket onwards varied much in importance; the holder being a churchman, he was not only engaged in the business of his diocese, but sometimes was away from England. Consequently, it became not unusual to place the personal custody of the great seal in the hands of a vice-chancellor or keeper; this, too, was the practice followed during a temporary vacancy in the chancellorship.

This office gradually developed into a permanent appointment, and the lord keeper acquired the right of discharging all the duties connected with the great seal. He was usually, though not necessarily, a peer, and held office during the king's pleasure, he was appointed merely by delivery of the seal, and not, like the chancellor, by patent. His status was definitely fixed (in the case of lord keeper Sir Nicholas Bacon) by an act of Elizabeth, which declared him entitled to " like place, pre-eminence, jurisdiction, execution of laws, and all other customs, commodities, and advantages" as the Lord Chancellor. In subsequent reigns the lord keeper was generally raised to the chancellorship, and retained the custody of the seal.

The last lord keeper was Sir Robert Henley (afterwards Earl of Northington), who was made chancellor on the accession of George III.

See also: Lord Chancellor, List of Lord Chancellors and Lord Keepers, Lord Privy Seal, Great Seal of the Realm, Privy Seal.